When you buy flour do you choose white specifically? Do you think that flour is white is good flour? In fact, this determination is incorrect.
White seems to be our ultimate pursuit for pasta, whether it's the cooking cakes made by Wu Da Lang or the noodle soup cooked by Du Shi Niang, all of them are white for beauty. In the old days, families are still proud to eat big white steamed bread. Could it be that the whiter the flour, the higher the quality? Of course not. The size of the flour particles, the pigment contained in itself, the storage process of polyphenol oxidase "black", accidentally mixed into the wheat husk particles will make the flour look not so white, but these do not affect its quality. Don't ask for flour like a little girl seeking whiteness.
It's not white, and that's for a reason
The flour we eat is taken from the endosperm of the wheat seed (the rest of the grain - the pericarp, seed coat, embryo and other tissues - is removed during milling, and is commonly referred to as bran), and the endosperm is a nutrient storage storehouse made up of starch and protein, whose job is to provide nutrients to the wheat seed as it germinates. The endosperm is a nutrient storehouse of starch and proteins that provides nutrients to the wheat seed as it sprouts, but now "moonlights" as a human food ration.
The color of flour is discussed in terms of its "original form" - the wheat endosperm. Generally speaking, the finer the flour grain, the better it reflects light, and the whiter it appears visually. However, not all wheat endosperm can be milled to the same fineness, and this is closely related to its protein content. The higher the protein content, the less likely the flour particles are to be finely ground, and the flour will naturally appear darker. Typically, durum wheat flour, which is high in protein, is darker than soft wheat flour in the same process.
In addition to the effect of granularity, the wheat endosperm itself contains some pigments, such as lutein and carotene. The yellowish color of new flour is caused by these substances. Over time, however, these substances degrade. This particular coloration cannot be found in flour that has been stored for some time. Some businesses will intentionally add carotenoids to their noodles, presumably to make the flour feel fresh to the consumer.
More interestingly, there are some unstable molecules lurking in the wheat endosperm that are waiting for a chance to act, and polyphenol oxidase (PPO) is one of them. They turn the colorless phenols they come into contact with into black "pigment". Those frostbitten bananas that turn black are the work of PPOs. The enzyme polyphenol oxidase in flour also works hard to convert phenolics, which is an important reason why flour and pasta become darker and darker.
Of course, the factors affecting the flour is not only the wheat endosperm itself, the color of the outer skin of the wheat is also a non-negligible influence. Especially in the case of red wheat, the hull is broken into small, colorful particles (called "bran stars"), which, if not cleanly sorted, can darken the flour. In contrast, the hulls of white wheat have less of an effect on the flour even if they are mixed in. In the white flour for the beauty of our country, the purchase price of white wheat is higher than red wheat is not difficult to understand. In fact, the protein content of red-grain wheat is usually higher, and they are by far the most widely grown type internationally. This probably has something to do with the fact that in Western cooking, wheat flour is mostly used for baking, with less attention paid to flour whiteness.
After the above analysis, you will still feel that the flour is white is a good flour it, in the future, when you pick the flour can not pick to the white, the more white does not mean the better.